The discussion centers on the value of older editions of "Basic Principles and Calculations of Chemical Engineering," specifically the 6th and 7th editions. Participants note that while the fundamental principles of chemical engineering likely remain unchanged, newer editions may include updated applications and improved problem sets. It's emphasized that if the textbook is required for a class, using an older edition could be problematic if the assigned problems differ. Some suggest considering international editions as a cost-saving option, although there are concerns about their quality, such as thinner paper and black-and-white printing. Opinions vary on the overall quality of newer editions, with some arguing that older textbooks often provide better content and clarity, while newer editions may prioritize profit over educational value. The conversation also touches on the broader context of textbook pricing and the challenges faced by students in affording necessary materials.